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Laboratory ventilation

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1. Think and describe what you would do in each of the following situations
which could happen in your laboratory.
a. You are working at your station and the 100-mL round-bottom flask in
which you are running a reaction in ether solvent suddenly catches fire.
b. The person working across the laboratory bench from you allows
hydrogen chloride gas to escape from his or her apparatus.
c. A reagent bottle is dropped, spilling concentrated sulfuric acid..
d. A hot solution 'bumps" splashing your face.

2. A laboratory has four hoods each of which is 39 in. wide. When the hood
door is open to a height of 8 in. and the hoods are operating, the average
air velocity through the hood face is 170 ft/min.
a. Evaluate the total ventilation rate for this room assuming that there
are no other exhausts.
b. The laboratory is designed for use by 30 students. Evaluate the air
available per student if the mixing factor is 0.3, and experiments
last for 3 hours.
c. An experiment is _considered in which each student would be
required to evaporate 7 mL of methylene chloride (CH2CI2).
Estimate the average concentration of methylene chloride. Look up
the TL V or the 1WA for methylene chloride and consider how the:
evaporation might be performed.

3. A laboratory has a ventilation system that provides 20 cubic meters for
each student during laboratory period. (This figure includes the mixing factor.) An
experiment is considered for this program that uses the following quantities of
materials A, B, and C. The TLV is also listed for each compound.
§substance Quantity (ma) TL V (mg/cubic meter)
A 400 1200
B 500 200
C 200 5
Assess the relative risks of these three compounds. Is there a likely need
for operations to be conducted in a hood if the compounds are assumed to be
entirely evaporated?

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